Characterization of total antioxidant capacity and (poly)phenolic compounds of differently pigmented rice varieties and their changes during domestic cooking

Abstract

In the recent years, the pigmented rice varieties are becoming more popular due to their antioxidant properties and phenolic content. In this study, we characterized the antioxidant capacity (TAC) and the phenolic profile in white, red and black rice varieties, and evaluated the effect of two cooking methods (i.e. "risotto" and boiling) on these compounds. Before the cooking, all the varieties contained several phenolic acids, whereas anthocyanins and flavonols were peculiar of black rice and flavan-3-ols of red rice. Among the rice varieties, the black had the highest TAC value. The content of (poly)phenolic compounds and TAC decreased after cooking in all three varieties, but to a lesser extent after the risotto method. As a consequence, the risotto cooking, which allows a complete absorption of water, would be a good cooking method to retain (poly)phenolic compounds and TAC in pigmented and non-pigmented whole-meal rice.

Keywords: (+)-Catechin (PubChem CID: 9064); (Poly)phenolic compounds; Cyanidin 3-O-glucoside (PubChem CID: 12303203); Cyanidin 3-O-rutinoside (PubChem CID: 441674); Domestic cooking; Ferulic acid (PubChem CID: 445858); Pigmented rice; Protocatechuic acid (PubChem CID: 72); Quercetin 3-O-glucoside (PubChem CID: 11557027); Sinapic acid (PubChem CID: 637775); Total antioxidant capacity; p-Coumaric acid (PubChem CID: 637542).